1. Field of the Invention.
This invention relates to mold holding and positioning means for use with a wax injector that fills the mold with a wax impression of a cavity pattern inside the mold.
2.Description of the Prior Art.
In the Lost Wax Process of metal casting the process is based upon a basic principle of making by carving and shaping wax into the pattern of the finished product desired.
The pattern is then surrounded by an investment plaster that hardens to form a mold.
After the mold is made it is heated in an oven and the wax melts away and is "lost". This leaves the mold empty and metal is then heated and cast into the cavity left by the "lost wax". In this way the cast metal will duplicate the pattern in the mold.
After the metal has been cast and setsup, the mold of hard plaster is broken and the metal duplicate is removed and finished by appropriate means.
In view of the fact that the hard mold is destroyed and the wax pattern is "lost", unless there were some way to preserve the wax pattern the shape and pattern would become truly lost.
Thus in order to preserve the wax pattern, if it is desirable to product additional casts of the pattern, a rubber of silicon mold is produced. In this way a number of wax impressions or patterns may be made and then placed in a number of investment plaster molds, or a family of impressions may be affixed to wax to form a tree. In this way the tree can be placed in an investment plaster, burned out so that a number of duplicate patterns may be cast.
It is known in the art that there are wax injector machines where the rubber or silicon mold is hand pressed to the machine for injection and forming of the wax pattern. There are also machines known that have the capability of forming a vacuum to remove impurities within the pattern cavity of the rubber mold.
Generally, in the prior art the pattern is placed into a frame and the rubber or silicon is poured around the pattern. After the vulcanization takes place, usually the mold is cut apart forming upper and lower halves each having outer flat surfaces. The wax pattern or other material pattern is removed and a channel from the pattern to a side of the mold is provided terminating in an outer sprue hole. A sprue hole is a tapered hole from the mold surface to the connecting channel.
Heretofore, the rubber duplicative molds have manually been held against wax injector machines which may result in bubbles in the wax and poor impressions or depending on the seat and pressure against the wax injector incomplete impressions. In other words there has been no consistency in the pressure.
In addition when the two halves are pressed together the downward pressure has not been consistent and faulty wax impressions are created through distortions of the cavities.
Finally, in some instances if the sprue hole is not properly positioned on a true center line, the engagement with the wax nozzle of the wax injector is faulty and a wax impression may not be properly formed.
Applicant is however aware of one patent which has attempted to provide a rubber mold holding means to be used with a wax injector. That patent is West German Patent No. 3024197 issued to Alexander Messing. From a translation the Messing structure disclosed will allow up and down as well as horizontal movement of a plate holding a mold, however there is no universal means for final alignment of a sprue hole with a wax nozzle. There must be exact positioning in order to align the hole and nozzle. This requires greater precision and time to accomplish the result. That invention is really limited to just a two dimensional movement.
Also the West German patent makes no provision for a swivel pressure plate to maintain the mold in a closed position. The clamp of the German patent appears to also be inflexible with a plate engaging the mold straight on with no swivel or universal adjustability for engaging the mold to assure proper closure pressure on the molds no matter how irregular the surface of the mold might be.